511
ACUS11 KWNS 211736
SWOMCD
SPC MCD 211735
MTZ000-211930-

Mesoscale Discussion 1354
NWS Storm Prediction Center Norman OK
1235 PM CDT Fri Jun 21 2024

Areas affected...Central Montana

Concerning...Severe potential...Watch likely

Valid 211735Z - 211930Z

Probability of Watch Issuance...80 percent

SUMMARY...A WW will likely be needed for Central MT this afternoon
as a few isolated supercells develop over the high terrain and move
east into an environment supportive of all severe hazards.

DISCUSSION...The current water vapor loop coupled with the RAP
upper-air analysis shows a subtle shortwave trough/vort max
approaching the Northern Rockies, with some morning convection
ongoing ahead of the wave. The boundary layer south and east of the
ongoing convection is characterized by mid 60s F surface
temperatures and mid-to-upper 50s F dewpoints, beneath steep
mid-level lapse rates of 8-9 C/km that are supportive of deep
convection later this afternoon. Morning soundings and SPC
Mesoanalysis indicate deep layer shear of 35-45 kts, suggesting
multicellular and supercellular storm modes are likely.

While ongoing convection over Judith Basin County appears to be
weakening, visible satellite indicates another region of developing
cumulus further to the west within a local minima of MLCINH,
suggesting additional development is likely within the next few
hours. RAP forecast profiles later this afternoon in Central MT
indicate buoyancy will increase to 2000 J/kg MLCAPE with deep layer
shear in the 45-50 kt range, suggesting a threat for supercells
capable of primarily damaging wind and hail, though also supportive
of tornadoes. Hodographs in South-Central MT are primarily
straight-line, indicating the potential for splitting supercells
capable of all hazards, while further north hodographs take on a
more curved shape in the low levels, supportive of a right-moving
supercell tornado threat.

Overall storm coverage is uncertain at this time, but a WW will
likely be needed later this afternoon for a few supercells that
develop and track eastward throughout the day, capable of all
hazards.

..Halbert/Weinman/Hart.. 06/21/2024

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...BYZ...GGW...TFX...

LAT...LON   48211193 48561099 48531030 48450901 47950766 47140682
            46660674 46310690 45900747 45540820 45460896 45870988
            46561058 46881100 47781190 48211193